1. Field of the Invention
The present invention relates to a method of reducing thickness of an unbroken rolling stock by longitudinal rolling according to which the rolling stock is deformed in the width direction by sidewise offset deformation regions of following one another, in the rolling stock displacement direction, rolls.
2. Description of the Prior Art
Different shapes of profiles, which are formed of a rolling stock, are well known. With material-intensive profiles such as, e.g., C-shape mounting rails, the portion of material costs in comparison with total manufacturing costs amounts to over 70%. Thus, saving of the material leads to a substantial reduction of the total manufacturing costs.
For statical reasons, a profile need not necessarily have a constant thickness or material thickness over its circumference. So, in less loaded sections, the profile thickness can be partially reduced and, thus, a certain amount of material can be saved.
A partial thickness reduction by single-stage rolling of a strip-shaped rolling stock in a cold rolling process does not make sense because due to the friction transverse to the roll and the stiffness of the flat rolling stock, the material reduction would take place only in one stretch in the longitudinal direction or in the displacement direction and would lead to hardening of material. This leads to inner stresses and a strong warping of the rolling stock.
German Publication DE 198 31 882 A1 discloses a method of producing a profile having a desired thickness from an unbroken rolling stock and according to which in order to form a thickness-reduced region, the rolling stock is deformed in the width direction by deformation regions of rolls which penetrate into a starting material over the rolling stock width to different depths.
The drawback of the method of the above-mentioned German Publication consists in that the adjustment or control of penetration of the roll deformation regions to different depths is expensive. Moreover, unevenesses, which are often undesirable, occur in the thickness-reduced sections, and in transition regions between the thickness-reduced sections and sections the thickness of which is not reduced, transverse to the rolling stock displacement direction. In addition, in order to produce sections with a constantly reduced thickness, a number of deformation steps, which are called passes, are necessary.
Accordingly, an object of the present invention is a method of reducing thickness of unbroken rolling stock and which is easily adjustable or controlled.
Another object of the present invention is a method of reducing thickness of an unbroken rolling stock and which has a smaller number of passes than the known method for producing a constant impression in the rolling stock.